The purpose of this study is to provide an actual basic data and helps for arranging the next generation OPAC's interface and function through improving the existing OPAC's interface and improvement in the domestic library. In this study, factors to be importantly considered for improving the OPAC's interface and function were examined based on the preceding studies on OPAC concept & development process, user's library use style, user use style of OPAC, and recognition on library's crisis, and actual condition investigation result. Also, the case analysis on the existing OPAC's interface and function was focused on the search window, search item, search method, alignment function, search result display and search result feedback. Also, the search interface and search function of the next generation OPAC which is provided by the recently-developed domestic and foreign library utilization, and the detailed case were analyzed in the aspect of Library 2.0 service. Finally, the measures for improving the existing OPAC's interface and function in domestic library were suggested.